Figure 2: An XPS spectra of two samples, BS004 being left in air 1 day after application of an eccrine fingerprint, and BS002 being a clean sample with no fingerprint. (normalised via the Mo 3p3/2 peak).

One can see that there are very little changes at this stage.

Figure 3: XPS spectra of the same sample (BS004) taken 1 day and 2 days after an application of an eccrine fingerprint. The sample was left in air over night. There has been no normalisation.

Figure 4: Showing several XPS spectra after a fingerprint was applied, and then left in air. Here are XPS spectra of a) a clean, uncorroded sample (BS002) b) a sample (BS004) which has an eccrine fingerprint, and has been left in air for 24 hours, c) the same sample as b) left for a further 15.5 hours in air c) the same sample as b) and c) left for a further 65 hours in air.

One can see there is very little changes, apart from a few anomalies, and no real development over time, possibly due to the act of cleaning the sample (BS002) with micro 90 before taking the XPS.